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February 1999

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Subject:
From:
Bev Christian <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Thu, 18 Feb 1999 20:51:58 -0500
Content-Type:
text/plain
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text/plain (52 lines)
Paul,
Presuming you cannot find an alternative relay socket from another source
with no holes, yes a temporary solder mask might work.  There is some cause
for concern because several of these are laced with ammonium hydroxide.
Your best bet is to screen a few with a copper mirror test and then get
someone like CSL to run a SIR/electromigration study for you, if the
supplier doesn't have these kind of results or you want an independent third
party result.

regards,
Bev Christian
Nortel Networks

        -----Original Message-----
        From:   Paul Wareham [SMTP:[log in to unmask]]
        Sent:   Thursday, February 18, 1999 7:13 PM
        To:     [log in to unmask]
        Subject:        [TN] Sealing sockets prior to potting.

        We've got a real problem with one product where we use potting
compound to encapsulate a PCB assembly.  The PCB has a few relay sockets
which have some openings at the bottom of the socket - not sealed.  When we
pour our potting compound into the unit, the potting creeps up the
connection pins into the connector body itself which really fouls up our
ability to plug in the relay.

        Getting the sockets sealed at the factory is not easy - big minimum
order and very costly.  We've tried a two stage potting procedure where we
pot only part way until the potting reaches the level of the socket - then
let it set, then pot the rest of the way.  This works to some degree but
with mixed results.

        We were thinking of sealing the bottom openings with a peelable
solder mask (Alpha Solder Stop 110) but some here were conerned that this
could adversly effect the tin plated brass pins on the socket or the solder
joints themselves.

        Has anyone else ever run into a similar problem?  Anyone think of
anything to try in order to help this situation?

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